The pricing is pay-as-you-go. Calls are charged on a per second basis with no connection fees or hidden fees of any kind. You will only be charged from your Roamer account when receiving calls from your home country or calling abroad with Roamer. Rates may vary depending on country.
Although most operators do not charge for call forwarding, some charges may still apply according to your operator of choice. You will need a minimal data plan on your foreign SIM card to activate Roamer and initiate outgoing calls. When calling locally and using the Internet you will only be charged from your foreign SIM card balance.
You can top-up your credit directly from the app. It’s an in-app purchase on iPhone and credit card/PayPal on Android. The packages are either 9.99, 19.99, 29.99, 49.99 EUR or US$ 12.99, 25.99, 38.99, 64.99.